1. Technical Field
The present invention relates to a supporting device for minimizing vibration, noise and external impact of a hard disk drive and more particularly to a disk drive assembly in which a supporting device having a damper is installed to protect data recorded on a disk from being lost and to protect the disk or the reading head from being damaged due to physical shocks resulted from external impact as well as vibrations and noise resulted from internal operations of the disk drive.
2. Background Art
As hard disk drives become smaller, and are used in more diverse environments, their ability to withstand physical shocks, vibrations and noise decreases, and consequently, the need to protect the disk drives against physical shocks, vibrations and noise becomes more apparent. Typically, noise arises from the rotation of the spindle motor and the disks, and also from the actuator that supports the read/write heads when a positioning operation is performed. While these are sources of acoustic noise in the typical disk drive, amplification can be caused by the mechanical base and cover. The acoustic noise could ultimately cause errors to arise in head-to-track positioning accuracy, thus limiting data recording densities. Similarly, physical shocks and vibrations from an external source could also cause errors to arise in the head-to-track positioning accuracy, and directly damage the disks which could cause loss of data, and damage to the heads which could end the life of the disk drive life, resulting in a total loss of data. Consequently, resistance to physical shocks, vibrations and noise is critical to protecting the disk, the head and the various bearings in a disk drive from damage. Conventional disk drives designed to reduce physical shocks, vibrations and noise are however, detailed, elaborate, expensive and often ineffective.
For example, U.S. Pat. No. 5,235,482 for Magnetic Disk Drive Incorporating A Mechanically Damped Base issued to Schmitz shows a typical design for a magnetic disk drive which reduces vibration and acoustic noise by providing a layer of damping material between a base assembly and a circuit board assembly for damping mechanical resonances. This design however has limited resistance to physical shocks from an external source. Similarly, U.S. Pat. No. 5,021,905 for Disk Drive Enclosure For Minimizing Stresses And A Vibration Damping Seal therefor issued to Sleger which envisions a vibration damping seal of a viscoelastic tape to seal a peripheral gap between adjacent base and cover of the hard disk drive in order to damp disk drive vibrations also has limited resistance to physical shocks and vibrations.
Variations on the same theme are shown in U.S. Pat. No. 4,491,888 for Memory Storage Apparatus Having Vibration-Damped Base Plate Arrangement issued to Brown et al., and Japanese Laid-Open 63-9094 for Information Reproducing Device issued to Inage. In U.S. Pat. No. 4,491,888, Brown discloses a base plate arrangement comprising an annular pad forming an air-tight seal at the edge of the base plate for damping resonant vibrations in the base plate, thereby providing stable servo operation. Similarly, in the Japanese Laid-Open 63-9094, Inage teaches the use of a plurality of springs connected to the inner ceiling of the hard disk drive to prevent vibrations caused from an external source from being transmitted to inner working mechanisms. Both Brown '888 and Inage '094, however, have limited resistance to noise and vibration resulted from the typical disk drive operation.
U.S. Pat. No. 4,598,328 for Mechanical Damper For Disk Drives Having Band Drive Actuators issued to Frangesh and U.S. Pat. No. 4,812,932 for Vibration Proof Supporting Structure For Disk-Type Information Memory Unit issued to Hishinuma et al., on the other hand, are designed to absorb vibrations of individual mechanical components of the disk drive as opposed to the operation of the entire disk drive itself. That is, Frangest '328 teaches an efficient mechanical damper of a stepper motor for damping unwanted oscillation so that the head of the disk drive could position at a selected data track. Similarly, Hishinuma '932 also teaches an efficient mechanical damper of a head assembly for alleviating the vibration caused by the actuator positioning operation. These conventional designs are however incapable of providing complete protection against physical shocks, vibrations and noise.
A more complete disk drive assembly is disclosed in WO 88/09551 for Disk Drive Architecture issued to Stefansky which provides a controlled environment resistant to physical shocks and thermally caused distortion. In Stefansky '551, however, the disk drive architecture is complex and has limited resistance to vibrations from an external source.